Yājñavalkya Śikṣā 14

14

vivṛttau cāvasāne tu ṛco'rdhe ca tathā pare
pade ca pādasaṃsthāne śūnyahasto vidhīyate

In a hiatus, at a pause at the end of a verse or sentence, and also at the half of a verse, and beyond that / at a word and at the end of a metrical quarter, an empty hand gesture is prescribed.